There is a need in seeking new compounds from natural sources to satisfy the demand for pharmaceutical, cosmetic, nutraceutical, agricultural and veterinary products, which has turned researchers and industries worldwide to develop bioprospecting, which is the study and sustainable use of plant, microorganism and animals biodiversity. In plants and vegetables, bioactive compounds are usually found in very low quantities, making extraction expensive and wasteful. It would be beneficial to have processes for extracting such bioactive compounds in high purity in ways that have minimal impact to the environment while at the same time increasing the yields of such compounds so to be commercially viable.
Saponins are natural glycosides that are widely distributed in the plant kingdom, given they have been detected in more than 500 genera of plants, including the Solanum genus. These compounds are attributed with phytoprotection functions in plants because of their fungicidal, antibiotic, insecticidal and molluscicidal properties.
Glycosides from the saponins possess an aglycone skeleton, which can be classified into three groups: steroidal, triterpene and glycoalkaloids. Solasodine glycosides are found in the glycoalkaloids group. Among the saponins that can be found in plants of the Solanum genus and which are monoglycosides and diglycosides of solasodine include saponins such as Solasonine (I), Solamargine (II), Solanine (III), Chaconine (IV) Tomatine (V) and Sycophantine (VI) whose structures are set forth below:

Saponins present in the plants of the Solanum genus are also useful as intermediates in the synthesis of contraceptive agents, corticosteroids, sex hormones and have also been proven effective in the treatment of various cancers in humans, showing high selectivity for tumor cells. Further, as antibiotics, these glycosides can inhibit the growth of Gram positive bacteria and have antiparasitic activity against microorganisms, such as Leishmania amazonenzis and several species of Schistosoma genus which cause leishmaniasis and schistosomiasis.
It has also been found that certain plant extracts of Solanum genus rich in saponins, have anti-inflammatory, hypotensive, hypoallergenic, antihistamine and antimicotic activity against fungi and yeast that cause dermatiphytosis and can be employed to improve skin health such as for the treatment of skin ulcerations caused by L. braziliensis. Other known uses include treatment of diabetes and high cholesterol.
It has further been found that the hydroalcoholic extracts of plants of the Solanum genus, exhibit molluscicidal activity against Bulinus camerunensis, and B. truncates and L. cubensis. Such mollusks are known to damage crops and transmit diseases.
Several processes have been described for obtaining saponins from plants of the Solanum genus, such as S. sodomaem, S. incanum, S. nigrum and S. robustum. Such processes are typically based on crushed or ground dry fruits, and extractions are performed using various solvents and purification steps. Thus for example, in U.S. Pat. Nos. 3,960,839 and 7,479,290, processes are mentioned wherein a first extraction takes place by mixing the crushed and milled dry fruits with methanol/water solutions, using a Soxhlet apparatus.
In such disclosed processes, a second extraction stage is employed using a pH 3-5 acetic acid or formic acid solutions, in which the residual plant material from the first extraction or the dry hydroalcoholic extract obtained was immersed, as mentioned in U.S. Pat. No. 7,479,290.
In other processes, the addition of strong bases (alkali, ammonium) to solutions resulting from the hydroalcoholic and acid extraction are performed in order to precipitate the crude Solasodine glycosides. Thus, for example, in the processes described in U.S. Pat. Nos. 7,479,290 and 7,078,063 and European Patent Number EP00200229, concentrated or diluted ammonia is added until a pH of 8 to 10 is reached and the formation of precipitate is induced by heating which can be purified by silica gel chromatography, liquid-liquid extraction and/or crystallization processes. The final products are presented as dried extracts rich in Solasodine glycosides with purity greater than 60%.
Although several processes with different solvents and conditions for the extraction and purification of Saponins from Solanum genus plants are known, the efficiency of such processes described is still insufficient and the purity of the obtained extracts have not typically exceeded 80%.
The processes set forth as part of the present invention involves easier, more selective and more efficient extraction and purification processes for obtaining Solasodine glycosides from Solanum genus plants, using low-toxicity solvents. The processes of the invention utilize fruits of Solanum at any stage of maturation without the requirement of undergoing initial drying stages. A further advantage of the claimed processes is that the glycosides extraction can be performed at room temperature and its purification does not require complete evaporation of solvents, thus obtaining an extract having purity in excess of 92% at higher yields than previously reported such as greater than 1%.